Numerical simulations of stellar SiO maser variability. Investigation of the effect of shocks

Abstract

A stellar hydrodynamic pulsation model has been combined with a SiO maser model in an attempt to calculate the temporal variability of SiO maser emission in the circumstellar envelope (CE) of a model AGB star. This study investigates whether the variations in local physical conditions brought about by shocks are the predominant contributing factor to SiO maser variability because, in this work, the radiative part of the pump is constant. We find that some aspects of the variability are not consistent with a pump provided by shock-enhanced collisions alone. In these simulations, gas parcels of relatively enhanced SiO abundance are distributed in a model CE by a Monte Carlo method, at a single epoch of the stellar cycle. From this epoch on, Lagrangian motions of individual parcels are calculated according to the velocity fields encountered in the model CE during the stellar pulsation cycle. The potentially masing gas parcels therefore experience different densities and temperatures, and have varying line-of-sight velocity gradients throughout the stellar cycle, which may or may not be suitable to produce maser emission. At each epoch (separated by 16.6 days), emission lines from the parcels are combined to produce synthetic spectra and VLBI-type images. We report here the results for v=1, J=1-0 (43-GHz) and J=2-1 (86-GHz) masers.

16 pages, 8 figures, accepted by A&A

Cited by in corpus (40)

• An Improved Model of SiO Maser Emission in Miras
• A movie of a star: multi-epoch VLBA imaging of the SiO masers towards the Mira variable TX Cam
• The Mira variable S Ori: Relationships between the photosphere, molecular layer, dust shell, and SiO maser shell at 4 epochs
• First Surface-resolved Results with the IOTA Imaging Interferometer: Detection of Asymmetries in AGB stars
• High resolution observations of SiO masers: comparing the spatial distribution at 43 and 86 GHz
• Resolving the extended atmosphere and the inner wind of Mira ($o$ Ceti) with long ALMA baselines
• SiO masers in TX Cam: Simultaneous VLBA observations of two 43 GHz masers at four epochs
• Circumstellar environment of the M-type AGB star R Dor. APEX spectral scan at $159.0-368.5$ GHz
• Multi-epoch imaging polarimetry of the SiO masers in the extended atmosphere of the Mira variable TX Cam
• SiO masers from AGB stars in the vibrationally excited v=1,v=2, and v=3 states
• Joint VLBA/VLTI Observations of the Mira Variable S Orionis
• SiO maser emission from red supergiants across the Galaxy: I. Targets in massive star clusters
• Axial Symmetry and Rotation in the SiO Maser Shell of IK Tauri
• Astrometrically Registered Simultaneous Observations of the 22 GHz H${}_2$O and the 43GHz SiO masers towards R Leonis Minoris using KVN and Source/Frequency Phase Referencing
• Mapping the circumstellar SiO maser emission in R Leo
• Inward Motions of the Compact SiO Masers Around VX Sagittarii
• VLBA imaging of the 3mm SiO maser emission in the disk-wind from the massive protostellar system Orion Source I
• Astrometrically registered maps of H2O and SiO masers toward VX Sagittarii
• Radio Stars: from kHz to THz
• A long-term VLBA monitoring campaign of the v=1, J=1-0 SiO masers toward TX Cam - I. Morphology and Shock Waves
• The 43GHz SiO maser in the circumstellar envelope of the AGB star R Cassiopeiae
• The Bulge Asymmetries and Dynamical Evolution (BAaDE) SiO Maser Survey at 86 GHz with ALMA
• A Polarization Survey of SiO Maser Variability in Evolved Stars
• SiO, 29SiO, and 30SiO emission from 67 oxygen-rich stars. A survey of 61 maser lines from 7 to 1 mm
• AGB interlopers in YSO catalogues hunted out by NEOWISE
• Quasi-simultaneous 43 and 86 GHz SiO Maser Observations and Potential Bias in the BAaDE Survey Are Resolved
• Continuous and Burst-like Accretion onto Substellar Companions in Mira Winds
• Simultaneous VLBA polarimetric observations of the v={1,2} J=1-0 and v=1, J=2-1 SiO maser emission toward VY CMa: maser morphology and pumping
• The maser emitting structure and time variability of the SiS lines J=14-13 and 15-14 in IRC+10216
• Using VLBI to Probe the Orion-KL Outflow on AU Scales
• Simultaneous VLBI Astrometry of H2O and SiO Masers toward the Semiregular Variable R Crateris
• The Science Case for Simultaneous mm-Wavelength Receivers in Radio Astronomy
• Relative astrometry of the J=1-0, v=1 and v=2 SiO masers towards R Leonis Minoris using VERA
• VLBI Observations of SiO Masers around AH Scorpii
• Pilot VLBI Survey of SiO v=3 J=1--0 Maser Emission around Evolved Stars
• Very fast variations of SiO maser emission in evolved stars
• The modulation of SiO maser polarization by Jovian planets
• Molecules and Chemistry in Red Supergiants
• High-angular-resolution ALMA imaging of the inhomogeneous dynamical atmosphere of the asymptotic giant branch star W Hya
• Multi-wavelength interferometry of evolved stars using VLTI and VLBA